[fedora-arm] arm at lists.fedoraproject.org

[Nick Clifton]

Hi Everyone,

   As part of a possible solution to the problem of how to bootstrap a
   hard-float ARM Fedora port, I am working on a script to create "fat"
   ARM binaries.  These are binaries which use the soft-float API, but
   which contain a special section which holds a hard-float API
   alternative.  Using one of the switches supported by the script it is
   possible to flip over the binaries, so that they now use the
   hard-float API and contain the soft-float API hidden away inside them.

   This is still a work in progress, but we thought that it would be a
   good idea to post the current version of the script to the list to see
   what people think, and to gather any feedback.  At the moment the
   script can only do simple compiling and linking.  It does not yet
   handle static or shared libraries, but that should come soon.

   Here is an example of how the script works:

     % cat float.c
     double add (double a, double b) { return a + b; }
     int main (void) { return (int) add (2.0, 3.0); }

     % fat-gcc -c float.c
     % fat-gcc float.o
     % ls -l float.o a.out
     -rwxrwx---. 1 nickc nickc 304778 Mar  1 17:58 a.out*
     -rw-------. 1 nickc nickc   2136 Mar  1 17:58 float.o

     % fat-gcc --fat-status float.o a.out
     fat-gcc.sh:  float.o: uses the soft API, contains a hard API 
alternative
     fat-gcc.sh:  a.out: uses the soft API, contains a hard API alternative

     % objdump -d a.out
     [snip]
     000081b8 <add>:
         81b8:       e92d4810        push    {r4, fp, lr}
         81bc:       e28db008        add     fp, sp, #8
         81c0:       e24dd014        sub     sp, sp, #20
         81c4:       e50b0014        str     r0, [fp, #-20]
    [snip]

    % fat-gcc --fat-swap a.out
    % fat-gcc --fat-status float.o a.out
    fat-gcc.sh:  float.o: uses the soft API, contains a hard API alternative
    fat-gcc.sh:  a.out: uses the hard API, contains a soft API alternative

     % objdump -d a.out
     [snip]
     000081b8 <add>:
         81b8:       e52db004        push    {fp}            ; (str fp, 
[sp, #-4]!)
         81bc:       e28db000        add     fp, sp, #0
         81c0:       e24dd014        sub     sp, sp, #20
         81c4:       ed0b0b03        vstr    d0, [fp, #-12]
    [snip]

Cheers
   Nick

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